The present invention relates to coiled measuring tape rules, more particularly the present invention relates to locking mechanisms for coiled measuring tape rules.
Coiled measuring tape rules are a standard item in the tool boxes of many carpenters, mechanics and artisians. Such coiled measuring tape rules are most conveniently utilized when they can be selectively locked in their uncoiled or extended configuration. Various locking mechanisms have been advanced for use with coiled taped measuring tape rules. These locking mechanisms may be divided into two categories; ones that are always locked and ones that can be locked and unlocked. Those that are always locked can lock by direct contact with the tape blade or by contact with the tape reel. This latter type is the least desirable as tape blades may shift once locked. Some currently manufactured tapes lock both against the tape reel and the tape blade. Herein the problem of tape movement is solved by the addition of a tape blade lock. Such tape blade lock is not strong enough to prevent the tape from moving if the lock against the tape reel is not engaged.
Exemplary of one type of locking mechanism is the system shown in U.S. Pat. No. 3,578,259 wherein a push button is located on the edge of the housing. When the tape is extended, one side of the button is pushed and the tape is locked in position. When it is desired to release the tape from its extended or uncoiled position, the opposite side of the button is pushed and the tape is allowed to recoil. Such prior art locking mechanisms, while utilitarian, are somewhat difficult to operate in that the user must first remember to lock the tape in its extended position. When finished, the user must then shift his hand grip on the tape housing to press the release side of the button thus allowing the coiled tape rule to return to its coiled configuration within the tape housing.
There is therefore a need in the art to provide an easy to use coiled tape measure rule incorporating a locking system wherein the tape portion is locked in its extended position whenever tape is dispensed from the tape measure housing. Such locking system should also provide for unlocking of the tape without changing the user's hand grip on the tape measure housing. Preferably such locking system should be de-activated by a button located on the side of the housing.